[Direct recording of electrical activity of human sinoatrial node]

The authors developed a method for recording the electrical activity directly from the human sinus node through the right subclavian vein. Electrical activity of the sinoatrial node (SA) was studied in 179 patients with CHD (angina pectoris, myocardial infarction). The sick-sinus syndrome (SSS) was revealed in 86 patients. The duration of slow deflection Sd, Ss -- P interval (from the onset of Ss to the onset of P wave), P -- A1 interval (from the onset of P wave to the first atrial spike) was prolonged in cases with SSS. The duration of Sd, Ss -- P and P -- A1 decreased after nitroglycerine and atropine administration but increased after benzodixin administration. The data on direct pacing of the SA node and the changes in the duration of phase Sd and Ss after the administration of drugs confirm that slow deflection Sd and rapid preatrial deflection Ss reflect the electrical activity of the SA node.